Question

我有以下代码，我想将for eaches转换为一个linq语句

        decimal originalCharges = 0;
        List<int> rdns = new List<int>()
        {
            1,
            2
        };
        foreach (var customerOrder in list)
        {
            foreach (CustomerBillTo billTo in customerOrder.BillTos)
            {
                originalCharges += billTo.Charges
                    .Where(charge => rdns.Contains(charge.RateCodeRdn))
                    .Sum(charge => charge.Amount);
            }
        }

这是我到目前为止所尝试的

        originalCharges = list.ForEach(co => co.BillTos.ForEach(bt => bt.Charges.Where(charge => rdns.Contains(charge.RateCodeRdn)).Sum(charge => charge.Amount)));

哪个给我一个错误，无法将类型“void”转换为“十进制”。

我认为我对第一个示例中的原始forEach循环中使用+ = for originalCharges感到困惑。

这可以在linq声明中完成吗？

originalCharges = list.ForEach(co => co.BillTos.ForEach( ));

Answer 1

你只需投射并压平收费金额并总结起来。

var originalCharges =
    (from customerOrder in list
    from billTo in customerOrder.BillTos
    from charge in billTo.Charges
    where rdns.Contains(charge.RateCodeRdn)
    select charge.Amount).Sum();

或者如果您更喜欢流利的方法：

var originalCharges =
    list.SelectMany(customerOrder =>
        customerOrder.BillTos.SelectMany(billTo =>
            billTo.Charges
                .Where(charge => rdns.Contains(charge.RateCodeRdn))
                .Select(charge => charge.Amount)
        )
    ).Sum();

Linq陈述问题

1 个答案: